"Plenty of room for interpretation and interpolation, if you so choose. So, bottom line, how do the controllers generally feel about it? I've never heard anyone say "Airliner 123, I need you to write down this number for not telling me that you're vacating an altitude." Yet
I want and am expecting the report leaving an altitude, even if it is 10 minutes later.
As far as the scraping on the chalk board "We're with you", you will probably get a quick lesson in ATC comunication from me and then most likely you will get to try it again. It usually goes something like this, "King Air 12K, we're with you is not in the book. When you check in you need to check in with your call sign, altitude leaving and your assigned altitude. Now lets try that initial call again."